US20040259275A1 - Method of forming ferroelectric film - Google Patents

Method of forming ferroelectric film Download PDF

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US20040259275A1
US20040259275A1 US10/800,722 US80072204A US2004259275A1 US 20040259275 A1 US20040259275 A1 US 20040259275A1 US 80072204 A US80072204 A US 80072204A US 2004259275 A1 US2004259275 A1 US 2004259275A1
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film
forming
pzt
complex oxide
ferroelectric
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Takeshi Kijima
Yasuaki Hamada
Eiji Natori
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Seiko Epson Corp
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Seiko Epson Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02172—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides
    • H01L21/02197—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides the material having a perovskite structure, e.g. BaTiO3
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/40—Oxides
    • C23C16/409—Oxides of the type ABO3 with A representing alkali, alkaline earth metal or lead and B representing a refractory metal, nickel, scandium or a lanthanide
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • C30B29/32—Titanates; Germanates; Molybdates; Tungstates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
    • H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
    • H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/314—Inorganic layers
    • H01L21/316—Inorganic layers composed of oxides or glassy oxides or oxide based glass
    • H01L21/31691—Inorganic layers composed of oxides or glassy oxides or oxide based glass with perovskite structure
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B53/00—Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B53/00—Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors
    • H10B53/30—Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors characterised by the memory core region
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L28/00—Passive two-terminal components without a potential-jump or surface barrier for integrated circuits; Details thereof; Multistep manufacturing processes therefor
    • H01L28/40—Capacitors
    • H01L28/55—Capacitors with a dielectric comprising a perovskite structure material

Definitions

  • the present invention relates to a method of forming a ferroelectric film using a metalorganic chemical vapor deposition method.
  • the present invention may provide a method of forming a ferroelectric film capable of providing a ferroelectric film including a PZT complex oxide with excellent crystal quality on a Pt metal film.
  • a method of forming a ferroelectric film including a complex oxide of lead zirconate titanate (PZT) family on a metal film formed of platinum (Pt) by using a metalorganic chemical vapor deposition method comprising:
  • FIG. 1 is a diagram schematically showing an MOCVD device used in one embodiment of the present invention.
  • FIGS. 2A to 2 D are cross-sectional views showing steps of forming a ferroelectric film according to one embodiment of the present invention.
  • FIG. 3 is a diagram illustrative of material supply timing and temperature raising history in an MOCVD device.
  • FIG. 4 shows observation results for surface morphology of a ferroelectric film according to one embodiment of the present invention.
  • FIG. 5 is a graph showing hysteresis characteristics of a ferroelectric film according to one embodiment of the present invention.
  • FIGS. 6A to 6 C are cross-sectional views showing steps of manufacturing a ferroelectric memory to which the steps in the method of forming a ferroelectric film according to one embodiment of the present invention are applied.
  • a method of forming a ferroelectric film including a complex oxide of lead zirconate titanate (PZT) family on a metal film formed of platinum (Pt) by using a metalorganic chemical vapor deposition method comprising:
  • an alloy film of Pb and Pt is formed on a metal film including Pt by using Pb which is one of elements of a complex oxide of PZT family. Since the alloy film has a lattice constant which easily allows lattice matching with a Pt film and PZT complex oxide, a strain of PZT complex oxide crystal formed on the alloy film caused by lattice mismatch can be reduced, whereby the interfacial state, which is one of the factors determining the fatigue characteristics of a ferroelectric film, can be improved. After forming the alloy film, the initial crystal nuclei of the PbTiO 3 complex oxide are formed on the alloy film by supplying Ti.
  • the crystallization temperature of a PZT complex oxide becomes higher as the composition ratio of Zr is increased. Therefore, crystal with excellent quality can be obtained in a comparatively low temperature using PbTiO 3 which does not include Zr.
  • the crystallization temperature of a PZT complex oxide can be reduced by reducing crystallization energy by utilizing the initial crystal nuclei of PbTiO 3 when forming the PZT complex oxide. Therefore, a ferroelectric film including a PZT complex oxide crystal having an excellent interfacial state with the Pt film and excellent quality can be obtained at a low crystallization temperature.
  • This method of forming a ferroelectric film may have the following features.
  • the alloy film may be formed in an inert gas atmosphere; and supply of an oxidizing gas may be started together with the supply of Ti. This makes it possible to effectively reduce oxidation of Pb, which easily bonds to oxygen and scatters into the atmosphere, in the step of forming the alloy film.
  • the alloy film may be formed at 400° C. or less. This makes it possible to effectively reduce scattering of Pb which easily vaporizes in a comparatively low temperature into the atmosphere in the step of forming the alloy film.
  • the initial crystal nuclei may be formed in an island pattern.
  • PbTiO 3 has a mechanical strength lower than that of the PZT complex oxide.
  • the crystal grown layer of the PZT complex oxide is formed to cover the initial crystal nuclei by dispersing the initial crystal nuclei in an island pattern, so that the reliability of the ferroelectric film in mechanical strength can be improved.
  • FIG. 1 is a view schematically showing a metalorganic chemical vapor deposition (MOCVD) device used for a method of forming a ferroelectric film according to the present embodiment.
  • MOCVD metalorganic chemical vapor deposition
  • An MOCVD device 100 includes a reaction chamber 10 and first to third material chambers 21 , 22 , and 23 . Heaters 40 for controlling the temperature of a substrate 50 inside the reaction chamber 10 are provided around the reaction chamber 10 . The first to third material chambers 21 , 22 , and 23 are connected with the reaction chamber 10 through a material supply line 31 .
  • the MOCVD device 100 is formed so that the flow rate of gas supplied to the reaction chamber 10 can be controlled by supplying argon (Ar) gas as a carrier gas to the reaction chamber 10 through a first gas supply line 32 .
  • An inert gas may be used as the carrier gas. Nitrogen (N 2 ) gas and the like can be given as examples of the carrier gas in addition to the argon gas.
  • the MOCVD device 100 is formed so that oxygen (O 2 ) gas as an oxidizing gas for forming a complex oxide of PZT family can be supplied to the reaction chamber 10 through a second gas supply line 33 .
  • oxygen (O 2 ) gas as an oxidizing gas for forming a complex oxide of PZT family can be supplied to the reaction chamber 10 through a second gas supply line 33 .
  • N 2 O gas or the like may be used as the oxidizing gas in addition to oxygen gas.
  • the material chamber 21 is charged with a lead (Pb) material 21 a .
  • a lead (Pb) material 21 a As examples of the Pb material 21 a , an alkyl-lead compound such as Pb(C 2 H 5 ) 4 , ⁇ -diketone-lead complex, and the like can be given.
  • the material chamber 22 is charged with a zirconium (Zr) material 22 a .
  • Zr material 22 a an alkoxide such as Zr(t-C 4 H 9 O) 4 and the like can be given.
  • the material chamber 23 is charged with a titanium (Ti) material 23 a .
  • Ti titanium
  • TiCl 4 an alkoxide such as Ti(i-C 3 H 7 O) 4 , and the like can be given.
  • FIGS. 2A to 2 D are cross-sectional views schematically showing steps of forming a ferroelectric film of PZT family according to the present embodiment.
  • a given substrate 50 on which a Pt metal film 60 is formed by sputtering or the like is provided as shown in FIG. 2A, and placed in the reaction chamber 10 of the MOCVD device 100 shown in FIG. 1.
  • a substrate such as a semiconductor substrate or a resin substrate may optionally be employed without specific limitations depending on the application of the ferroelectric film.
  • the Pb material 21 a is supplied to the reaction chamber 10 together with Ar gas as the carrier gas, as shown in a section A in FIG. 3, to form a PbPt 3 alloy film 61 , which is the alloy of Pt and Pb, on the Pt metal film 60 , as shown in FIG. 2B.
  • the atmosphere inside the reaction chamber 10 is preferably an inert gas atmosphere containing no O 2 gas as the oxidizing gas. The reason therefor is as follows. Since Pb easily bonds to oxygen, if the oxygen partial pressure in the atmosphere is high, Pb deposited on the Pt metal film 60 bonds to oxygen and scatters into the atmosphere.
  • Pb which makes up the alloy film 61 can be prevented from being released to the atmosphere by performing the step of forming the alloy film 61 in a non-oxidizing atmosphere formed by an inert gas such as Ar gas or N 2 gas.
  • the heaters 40 are controlled so that the temperature of the substrate 50 is preferably 400° C. or less, and still more preferably about 150° C. Since Pb easily vaporizes in a comparatively low temperature region, it is also important to prevent Pb from scattering in the step of forming the alloy film 61 from the viewpoint of temperature.
  • the Ti material 22 a and O 2 gas as the oxidizing gas are supplied to form initial crystal nuclei 71 of a PbTiO 3 complex oxide on the alloy film 61 , as shown in FIG. 2C.
  • the initial crystal nuclei 71 are preferably formed on the alloy film 61 in an island pattern.
  • PbTiO 3 can reduce the crystallization temperature of the PZT complex oxide.
  • PbTiO 3 has a mechanical strength lower than that of the PZT complex oxide.
  • the Zr material 23 a is supplied as shown in a section C in FIG. 3 to form the crystal grown layer 72 of a Pb (ZrTi)O 3 complex oxide on the initial crystal nuclei 71 as shown in FIG. 2D, whereby a PZT ferroelectric film can be obtained.
  • the alloy film 61 has a lattice constant which easily allows lattice matching with the Pt metal film 60 and the PZT complex oxide, a strain of the PZT complex oxide crystal formed on the alloy film 61 caused by lattice mismatch can be reduced, whereby the interfacial state, which is one of the factors that determine the fatigue characteristics of the ferroelectric film, can be improved.
  • a ferroelectric film of the present embodiment since the crystallization energy can be reduced by utilizing the initial crystal nuclei 71 of PbTiO 3 when forming the crystal grown layer 72 of the PZT complex oxide, the crystallization temperature of the PZT complex oxide can be reduced. Therefore, a ferroelectric film including the crystal grown layer 72 of the PZT complex oxide having an excellent interfacial state and excellent crystal quality can be formed on the Pt metal film 60 at a low crystallization temperature by using this method of the present embodiment.
  • a PbZr 0.3 Ti 0.7 O 3 (PZT) film with a thickness of 150 nm was formed by using the MOCVD method using the method of forming a ferroelectric film of the present embodiment according to the above-described deposition steps.
  • the PZT film was confirmed to have excellent surface morphology as shown in FIG. 4 and excellent hysteresis characteristics as shown in FIG. 5.
  • the hysteresis characteristics were measured after forming a Pt upper electrode with a diameter of 100 ⁇ m and a thickness of 100 nm on the PZT film.
  • the method of forming a ferroelectric film of the present embodiment may be applied to a method of manufacturing a ferroelectric memory or a piezoelectric device using the ferroelectric film.
  • An example in which the method of forming a ferroelectric film of the present embodiment is applied to the method of manufacturing a ferroelectric memory is described below.
  • FIGS. 6A to 6 C are cross-sectional views schematically showing an example of manufacturing steps of a ferroelectric memory according to this example.
  • the PbPt 3 alloy film 61 , the PbTiO 3 initial crystal nuclei 71 , and the PZT crystal grown layer 72 are formed in that order on the substrate 50 , on which the Pt metal film 60 as a lower electrode of a ferroelectric capacitor 80 is formed, by using the above-described method of forming a ferroelectric film.
  • a Pt metal film 62 as an upper electrode of the ferroelectric capacitor 80 is formed on the PZT crystal grown layer 72 .
  • a semiconductor substrate 51 on which a cell select transistor 56 is formed may be used, as shown in FIG. 6A.
  • the transistor 56 may include a source/drain 53 , a gate oxide film 54 , and a gate electrode 55 .
  • a stack structure may be employed in which a plug electrode 57 is formed of tungsten or the like on one of the source/drains 53 of the transistor 56 so as to be connected with the Pt metal film 60 as the lower electrode of the ferroelectric capacitor 80 .
  • the transistors 56 are separated in cell units by an element isolation region 52 .
  • a first interlayer dielectric 58 may be formed of an oxide film or the like on the transistor 56 .
  • the ferroelectric capacitor 80 is patterned into a desired size and shape.
  • a hydrogen barrier film 91 is formed to cover the ferroelectric capacitor 80
  • a second interlayer dielectric 92 is formed.
  • Metal interconnect layers 93 and 94 for connecting the ferroelectric capacitor 80 and the transistor 56 with the outside through through-holes formed in the second interlayer dielectric 92 are formed to obtain a ferroelectric memory. According to the steps in this example, since a PZT ferroelectric film having an excellent crystal quality is formed, a ferroelectric memory with excellent characteristics can be realized.
  • This example illustrates the steps of forming a so-called 1T1C type ferroelectric memory.
  • the method of forming a ferroelectric film of the present embodiment may also be applied to steps of manufacturing ferroelectric memories using various cell structures such as 2T2C type and simple matrix type (cross-point type).

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Abstract

A method of forming a ferroelectric film including a complex oxide of PZT family on a metal film formed of Pt by using a metalorganic chemical vapor deposition method. At first, supply of Pb is started to form an alloy film of Pb and Pt on the metal film. Supply of Ti is then started to form an initial crystal nuclei of PbTiO3 on the alloy film. Then, supply of Zr is started to form a crystal grown layer of the complex oxide of PZT family on the initial crystal nuclei.

Description

  • Japanese Patent Application No. 2003-71953, filed on Mar. 17, 2003, is hereby incorporated by reference in its entirety. [0001]
    • BACKGROUND OF THE INVENTION
  • The present invention relates to a method of forming a ferroelectric film using a metalorganic chemical vapor deposition method. [0002]
  • In recent years, as a technology of forming a ferroelectric film which is expected to be applied to a ferroelectric memory and a piezoelectric device, a deposition technology using a metalorganic chemical vapor deposition (MOCVD) method used in the crystal growth technology of compound semiconductors has attracted attention in order to improve mass production capability. [0003]
  • However, in the case of depositing a complex oxide of lead zirconate titanete (PZT) family on a Pt metal film used as an electrode material, since the crystal lattice matching between the complex oxide of PZT family and the Pt metal film is poor, it is difficult to obtain a ferroelectric film having an excellent crystallization state by using a conventional deposition technology using the MOCVD method. In the case of depositing a complex oxide of PZT family by using the MOCVD method, the complex oxide of PZT family is generally deposited by supplying material gases for all the constituent elements at the same time. In the case of depositing a complex oxide of PZT family on a Pt metal film, a technology of forming a TiO[0004] x film between the Pt metal film and the PZT complex oxide crystal as a buffer layer by supplying only a Ti material and an oxidizing gas has been proposed in order to reduce the above-described lattice mismatch. However, since the orientation of the crystal of the TiOx film may adversely affect the orientation of the PZT complex oxide crystal, a technology which can replace this technology has been demanded.
    • BRIEF SUMMARY OF THE INVENTION
  • The present invention may provide a method of forming a ferroelectric film capable of providing a ferroelectric film including a PZT complex oxide with excellent crystal quality on a Pt metal film. [0005]
  • According to one aspect of the present invention, there is provided a method of forming a ferroelectric film including a complex oxide of lead zirconate titanate (PZT) family on a metal film formed of platinum (Pt) by using a metalorganic chemical vapor deposition method, the method comprising: [0006]
  • starting supply of lead (Pb) to form an alloy film of Pb and Pt on the metal film; [0007]
  • starting supply of titanium (Ti) to form initial crystal nuclei of a lead titanate (PbTiO[0008] 3) on the alloy film; and
  • starting supply of zirconium (Zr) to form a crystal grown layer of the complex oxide of PZT family on the initial crystal nuclei.[0009]
    • BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
  • FIG. 1 is a diagram schematically showing an MOCVD device used in one embodiment of the present invention. [0010]
  • FIGS. 2A to [0011] 2D are cross-sectional views showing steps of forming a ferroelectric film according to one embodiment of the present invention.
  • FIG. 3 is a diagram illustrative of material supply timing and temperature raising history in an MOCVD device. [0012]
  • FIG. 4 shows observation results for surface morphology of a ferroelectric film according to one embodiment of the present invention. [0013]
  • FIG. 5 is a graph showing hysteresis characteristics of a ferroelectric film according to one embodiment of the present invention. [0014]
  • FIGS. 6A to [0015] 6C are cross-sectional views showing steps of manufacturing a ferroelectric memory to which the steps in the method of forming a ferroelectric film according to one embodiment of the present invention are applied.
    • DETAILED DESCRIPTION OF THE EMBODIMENT
  • According to one embodiment of the present invention, there is provided a method of forming a ferroelectric film including a complex oxide of lead zirconate titanate (PZT) family on a metal film formed of platinum (Pt) by using a metalorganic chemical vapor deposition method, the method comprising: [0016]
  • starting supply of lead (Pb) to form an alloy film of Pb and Pt on the metal film; [0017]
  • starting supply of titanium (Ti) to form initial crystal nuclei of a lead titanate (PbTiO[0018] 3) on the alloy film; and
  • starting supply of zirconium (Zr) to form a crystal grown layer of the complex oxide of PZT family on the initial crystal nuclei. [0019]
  • According to this method, an alloy film of Pb and Pt is formed on a metal film including Pt by using Pb which is one of elements of a complex oxide of PZT family. Since the alloy film has a lattice constant which easily allows lattice matching with a Pt film and PZT complex oxide, a strain of PZT complex oxide crystal formed on the alloy film caused by lattice mismatch can be reduced, whereby the interfacial state, which is one of the factors determining the fatigue characteristics of a ferroelectric film, can be improved. After forming the alloy film, the initial crystal nuclei of the PbTiO[0020] 3 complex oxide are formed on the alloy film by supplying Ti. It is known that the crystallization temperature of a PZT complex oxide becomes higher as the composition ratio of Zr is increased. Therefore, crystal with excellent quality can be obtained in a comparatively low temperature using PbTiO3 which does not include Zr. In the method of forming a ferroelectric film according to this embodiment, the crystallization temperature of a PZT complex oxide can be reduced by reducing crystallization energy by utilizing the initial crystal nuclei of PbTiO3 when forming the PZT complex oxide. Therefore, a ferroelectric film including a PZT complex oxide crystal having an excellent interfacial state with the Pt film and excellent quality can be obtained at a low crystallization temperature.
  • This method of forming a ferroelectric film may have the following features. [0021]
  • (A) The alloy film may be formed in an inert gas atmosphere; and supply of an oxidizing gas may be started together with the supply of Ti. This makes it possible to effectively reduce oxidation of Pb, which easily bonds to oxygen and scatters into the atmosphere, in the step of forming the alloy film. [0022]
  • (B) The alloy film may be formed at 400° C. or less. This makes it possible to effectively reduce scattering of Pb which easily vaporizes in a comparatively low temperature into the atmosphere in the step of forming the alloy film. [0023]
  • (C) The initial crystal nuclei may be formed in an island pattern. PbTiO[0024] 3 has a mechanical strength lower than that of the PZT complex oxide. The crystal grown layer of the PZT complex oxide is formed to cover the initial crystal nuclei by dispersing the initial crystal nuclei in an island pattern, so that the reliability of the ferroelectric film in mechanical strength can be improved.
  • Embodiment of the present invention is described below in more detail with reference to the drawings. [0025]
  • 1. Forming Device [0026]
  • FIG. 1 is a view schematically showing a metalorganic chemical vapor deposition (MOCVD) device used for a method of forming a ferroelectric film according to the present embodiment. [0027]
  • An [0028] MOCVD device 100 includes a reaction chamber 10 and first to third material chambers 21, 22, and 23. Heaters 40 for controlling the temperature of a substrate 50 inside the reaction chamber 10 are provided around the reaction chamber 10. The first to third material chambers 21, 22, and 23 are connected with the reaction chamber 10 through a material supply line 31. The MOCVD device 100 is formed so that the flow rate of gas supplied to the reaction chamber 10 can be controlled by supplying argon (Ar) gas as a carrier gas to the reaction chamber 10 through a first gas supply line 32. An inert gas may be used as the carrier gas. Nitrogen (N2) gas and the like can be given as examples of the carrier gas in addition to the argon gas. The MOCVD device 100 is formed so that oxygen (O2) gas as an oxidizing gas for forming a complex oxide of PZT family can be supplied to the reaction chamber 10 through a second gas supply line 33. N2O gas or the like may be used as the oxidizing gas in addition to oxygen gas.
  • The [0029] material chamber 21 is charged with a lead (Pb) material 21 a. As examples of the Pb material 21 a, an alkyl-lead compound such as Pb(C2H5)4, β-diketone-lead complex, and the like can be given.
  • The [0030] material chamber 22 is charged with a zirconium (Zr) material 22 a. As examples of the Zr material 22 a, an alkoxide such as Zr(t-C4H9O)4 and the like can be given.
  • The [0031] material chamber 23 is charged with a titanium (Ti) material 23 a. As examples of the Ti material 23 a, TiCl4, an alkoxide such as Ti(i-C3H7O)4, and the like can be given.
  • 2. PZT Ferroelectric film [0032]
  • FIGS. 2A to [0033] 2D are cross-sectional views schematically showing steps of forming a ferroelectric film of PZT family according to the present embodiment.
  • In this method, a given [0034] substrate 50 on which a Pt metal film 60 is formed by sputtering or the like is provided as shown in FIG. 2A, and placed in the reaction chamber 10 of the MOCVD device 100 shown in FIG. 1. As the substrate 50, a substrate such as a semiconductor substrate or a resin substrate may optionally be employed without specific limitations depending on the application of the ferroelectric film.
  • In the [0035] MOCVD device 100, the Pb material 21 a is supplied to the reaction chamber 10 together with Ar gas as the carrier gas, as shown in a section A in FIG. 3, to form a PbPt3 alloy film 61, which is the alloy of Pt and Pb, on the Pt metal film 60, as shown in FIG. 2B. The atmosphere inside the reaction chamber 10 is preferably an inert gas atmosphere containing no O2 gas as the oxidizing gas. The reason therefor is as follows. Since Pb easily bonds to oxygen, if the oxygen partial pressure in the atmosphere is high, Pb deposited on the Pt metal film 60 bonds to oxygen and scatters into the atmosphere. Specifically, in this method, Pb which makes up the alloy film 61 can be prevented from being released to the atmosphere by performing the step of forming the alloy film 61 in a non-oxidizing atmosphere formed by an inert gas such as Ar gas or N2 gas. In this method, the heaters 40 are controlled so that the temperature of the substrate 50 is preferably 400° C. or less, and still more preferably about 150° C. Since Pb easily vaporizes in a comparatively low temperature region, it is also important to prevent Pb from scattering in the step of forming the alloy film 61 from the viewpoint of temperature.
  • As shown in a section B in FIG. 3, the [0036] Ti material 22 a and O2 gas as the oxidizing gas are supplied to form initial crystal nuclei 71 of a PbTiO3 complex oxide on the alloy film 61, as shown in FIG. 2C. The initial crystal nuclei 71 are preferably formed on the alloy film 61 in an island pattern. PbTiO3 can reduce the crystallization temperature of the PZT complex oxide. However, PbTiO3 has a mechanical strength lower than that of the PZT complex oxide. In this method, since a crystal grown layer 72 of the PZT complex oxide is formed to cover the initial crystal nuclei 71 by dispersing the initial crystal nuclei 71 in an island pattern, reliability of the ferroelectric film can be improved from the viewpoint of mechanical strength.
  • The [0037] Zr material 23 a is supplied as shown in a section C in FIG. 3 to form the crystal grown layer 72 of a Pb (ZrTi)O3 complex oxide on the initial crystal nuclei 71 as shown in FIG. 2D, whereby a PZT ferroelectric film can be obtained.
  • As described above, according to the method of forming a ferroelectric film of the present embodiment, since the [0038] alloy film 61 has a lattice constant which easily allows lattice matching with the Pt metal film 60 and the PZT complex oxide, a strain of the PZT complex oxide crystal formed on the alloy film 61 caused by lattice mismatch can be reduced, whereby the interfacial state, which is one of the factors that determine the fatigue characteristics of the ferroelectric film, can be improved. In the method of forming a ferroelectric film of the present embodiment, since the crystallization energy can be reduced by utilizing the initial crystal nuclei 71 of PbTiO3 when forming the crystal grown layer 72 of the PZT complex oxide, the crystallization temperature of the PZT complex oxide can be reduced. Therefore, a ferroelectric film including the crystal grown layer 72 of the PZT complex oxide having an excellent interfacial state and excellent crystal quality can be formed on the Pt metal film 60 at a low crystallization temperature by using this method of the present embodiment.
  • A PbZr[0039] 0.3Ti0.7O3 (PZT) film with a thickness of 150 nm was formed by using the MOCVD method using the method of forming a ferroelectric film of the present embodiment according to the above-described deposition steps. As a result, the PZT film was confirmed to have excellent surface morphology as shown in FIG. 4 and excellent hysteresis characteristics as shown in FIG. 5. The hysteresis characteristics were measured after forming a Pt upper electrode with a diameter of 100 μm and a thickness of 100 nm on the PZT film.
  • The method of forming a ferroelectric film of the present embodiment may be applied to a method of manufacturing a ferroelectric memory or a piezoelectric device using the ferroelectric film. An example in which the method of forming a ferroelectric film of the present embodiment is applied to the method of manufacturing a ferroelectric memory is described below. [0040]
  • 3. Application to Method of Manufacturing Ferroelectric Memory [0041]
  • FIGS. 6A to [0042] 6C are cross-sectional views schematically showing an example of manufacturing steps of a ferroelectric memory according to this example.
  • In this example, as shown in FIG. 6A, the PbPt[0043] 3 alloy film 61, the PbTiO3 initial crystal nuclei 71, and the PZT crystal grown layer 72 are formed in that order on the substrate 50, on which the Pt metal film 60 as a lower electrode of a ferroelectric capacitor 80 is formed, by using the above-described method of forming a ferroelectric film. A Pt metal film 62 as an upper electrode of the ferroelectric capacitor 80 is formed on the PZT crystal grown layer 72. As the substrate 50, a semiconductor substrate 51 on which a cell select transistor 56 is formed may be used, as shown in FIG. 6A. The transistor 56 may include a source/drain 53, a gate oxide film 54, and a gate electrode 55. A stack structure may be employed in which a plug electrode 57 is formed of tungsten or the like on one of the source/drains 53 of the transistor 56 so as to be connected with the Pt metal film 60 as the lower electrode of the ferroelectric capacitor 80. In the substrate 50, the transistors 56 are separated in cell units by an element isolation region 52. A first interlayer dielectric 58 may be formed of an oxide film or the like on the transistor 56.
  • In this example, as shown in FIG. 6B, the [0044] ferroelectric capacitor 80 is patterned into a desired size and shape. As shown in FIG. 6C, a hydrogen barrier film 91 is formed to cover the ferroelectric capacitor 80, and a second interlayer dielectric 92 is formed. Metal interconnect layers 93 and 94 for connecting the ferroelectric capacitor 80 and the transistor 56 with the outside through through-holes formed in the second interlayer dielectric 92 are formed to obtain a ferroelectric memory. According to the steps in this example, since a PZT ferroelectric film having an excellent crystal quality is formed, a ferroelectric memory with excellent characteristics can be realized.
  • This example illustrates the steps of forming a so-called 1T1C type ferroelectric memory. The method of forming a ferroelectric film of the present embodiment may also be applied to steps of manufacturing ferroelectric memories using various cell structures such as 2T2C type and simple matrix type (cross-point type). [0045]
  • The preferred embodiment of the present invention is described above. However, the present invention is not limited to the above-described embodiment. The present invention may be embodied in various modified forms within the scope of the present invention. [0046]

Claims (4)

What is claimed is:
1. A method of forming a ferroelectric film including a complex oxide of lead zirconate titanate (PZT) family on a metal film formed of platinum (Pt) by using a metalorganic chemical vapor deposition method, the method comprising:
starting supply of lead (Pb) to form an alloy film of Pb and Pt on the metal film;
starting supply of titanium (Ti) to form initial crystal nuclei of a lead titanate (PbTiO3) on the alloy film; and
starting supply of zirconium (Zr) to form a crystal grown layer of the complex oxide of PZT family on the initial crystal nuclei.
2. The method of forming a ferroelectric film as defined in claim 1, wherein:
the alloy film is formed in an inert gas atmosphere; and
supply of an oxidizing gas is started together with the supply of Ti.
3. The method of forming a ferroelectric film as defined in claim 1,
wherein the alloy film is formed at 400° C. or less.
4. The method of forming a ferroelectric film as defined in claim 1,
wherein the initial crystal nuclei are formed in an island pattern.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070287248A1 (en) * 2005-02-08 2007-12-13 Tokyo Electron Limited Method for manufacturing capacity element, method for manufacturing semiconductor device and semiconductor-manufacturing apparatus

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* Cited by examiner, † Cited by third party
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JP4937533B2 (en) * 2005-06-16 2012-05-23 東京エレクトロン株式会社 Semiconductor device manufacturing method and computer storage medium
US7592273B2 (en) * 2007-04-19 2009-09-22 Freescale Semiconductor, Inc. Semiconductor device with hydrogen barrier and method therefor
JP2009117768A (en) * 2007-11-09 2009-05-28 Toshiba Corp Semiconductor memory device and method of manufacturing the same
WO2020179210A1 (en) * 2019-03-07 2020-09-10 アドバンストマテリアルテクノロジーズ株式会社 Film structure, piezoelectric film and superconductor film

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5714194A (en) * 1993-06-04 1998-02-03 Sharp Kabushiki Kaisha Method for producing a ferroelectric thin film
US20030175425A1 (en) * 2000-08-09 2003-09-18 Toru Tatsumi Vapor phase deposition method for metal oxide dielectric film

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5714194A (en) * 1993-06-04 1998-02-03 Sharp Kabushiki Kaisha Method for producing a ferroelectric thin film
US20030175425A1 (en) * 2000-08-09 2003-09-18 Toru Tatsumi Vapor phase deposition method for metal oxide dielectric film

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070287248A1 (en) * 2005-02-08 2007-12-13 Tokyo Electron Limited Method for manufacturing capacity element, method for manufacturing semiconductor device and semiconductor-manufacturing apparatus

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